1. Field of the Invention
The invention relates to the field of packaging bags.
2. Description of Related Art
Numerous packaging bags and numerous systems for manufacturing them have already been proposed.
For thin bags, usually flat, in a filled state, the known means give overall satisfaction. In this case, the bags are generally made from two flat webs welded together along three sides and bearing means for sealing, for example complementary male/female sections at the opening of the bags.
On the other hand until now, the making of bags for bulky items, irrespective of their nature, has proved unsatisfactory, despite numerous studies in this very specific field.
In particular, such bags often require relatively thick walls, and it is not easy to attach means for sealing to such walls.
This applying of the means for sealing is all the more delicate when the means for applying are not located at the opening of the packaging bag, but on a surface of the bag.
We have diagrammatically illustrated in the annexed FIG. 1 a known technique for manufacturing bags comprising means for sealing 5 attached to a wall 3 of the packaging bag 1, and not at the opening 2 of the packaging bag.
The means for sealing 5 are welded or stuck to points 6 on the front wall 3 of the bag 1.
The points of application are made on the means for applying 7 of the means for sealing 5. These means for applying 7 comprise films, for example made in plastic.
The means for sealing 5 can also comprise means 8 forming runners facilitating the opening and closing of the means for sealing 5.
Examples of such known bags are disclosed and illustrated in documents U.S. Pat. No. 4,335,817 and EP 0 843 636.
The bags, according to the prior art, however, comprise inconveniences.
Notably, the points of application 6 are not entirely sound.
Such bags do not envisage the applying of means for applying on bags comprising double-layer walls, that meaning double ply bags.